1. Field of the Invention
The present invention relates to a radiation image pickup device and a radiation image pickup system, and more particularly to a radiation image pickup device and a radiation image pickup system which convert radiations such as x-rays, xcex1-rays, xcex2-rays or xcex3-rays into a light of a photosensor-detectable wavelength such as a visible light by means of a wavelength converting member such as a scintillator, and detect the converted light through an optical system by the photosensor.
2. Related Background Art
Up to now, x-ray image pickup devices employed for non-destructive examination such as medical diagnosis or internal examination have been mainly systems in which x-rays are projected through an object to be examined (hereinafter simply referred to as xe2x80x9cobjectxe2x80x9d) such as a human body, and the x-rays which have been transmitted through the object are converted into light by a phosphor, and a film is exposed to the converted light (hereinafter referred to xe2x80x9cfilm systemxe2x80x9d).
FIG. 1 is a schematically structural view showing an example of an x-ray image pickup device of the film system. Referring to FIG. 1, reference numeral 501 denotes an x-ray source; 502, an object such as a human body (patient) through which x-rays emitted from the x-ray source 501 are projected; 503, a grid designed so that a material that absorbs x-rays and a material that transmits x-rays are alternately disposed for removing scattered x-ray components to improve the resolution; 504, a scintillator that absorbs the x-rays to emit a light; and 505, a film that receives the light from the scintillator 504.
The film system thus structured suffers from problems stated below.
First, because an x-ray image of the object, such as a patient, is captured on the film, it is necessary to develop the film in order to obtain the x-ray image, thus taking labor and time. In the case where the object, such as a patient, is in motion during the radiography or where appropriate exposure is not attained, the radiography must be conducted once more after development of the film. The setting for re-radiography not only lowers the radiography efficiency but also increases the work required for each object, such as a patient, and prevents the efficiency of medical examination in a hospital from being improved.
In addition, it is necessary that the radiographed x-ray image film is kept within an enterprise or a hospital, and in particular, it is necessary that the photographed x-ray image film is kept within the hospital for a given period of time. As a result, the number of films kept in the hospital becomes very large, and there is further required that the films can be taken in and out every time the patient visits hospital. Accordingly, the efficiency of management of the films within the hospital must be also improved.
In addition, there is a case where when the patient changes hospitals, the x-ray films radiographed up to that time must be forwarded to the another hospital through some means in order to prevent re-radiography.
In order to solve the above problems, the digitalization of x-ray image information has been increasingly demanded in recent years. If the x-ray information can be digitalized, not only the x-ray image information can be managed by using a recording medium such as a photo-magnetic disc but also the state of an obtained image can be judged instantly. As a result, a medical doctor or the like can obtain the x-ray image information of the object such as a patient with a preferred angle or amount of exposure at a real time.
Also, if a facsimile machine or other communication systems are employed, it is possible to transfer the x-ray image information to a remote hospital or enterprise in a short period of time. In addition, if the obtained digital x-ray image information is picture-processed by using a computer, diagnosis can be conducted with higher precision, thereby solving the above problems with the film system.
As a device for digitalizing the x-ray information, there been proposed an x-ray image pickup device in which x-rays that have been transmitted by the object are irradiated to and absorbed by a wavelength converting member such as a scintillator, and are then wavelength-converted into a light such as a visible light which is in proportion to the intensity of the irradiated/absorbed x-rays, and in which the light is received by a solid image pickup element such as a CCD which is sensitive to the wavelength of the light, and then converted into a digital information. Also, a medical image generally requires a large number of pixels of, for example, about 2,000xc3x973,000 (6,000,000).
The present invention has been made to solve the above problems with the conventional devices, and therefore an object of the present invention is to provide a radiation image pickup device and a radiation image pickup system which can preferably be employed in an x-ray image pickup device that demands a large number of pixels.
Another object of the present invention is to provide a large-area, compact radiation image pickup device in which an imaging optical system is disposed between a solid image pickup element and a wavelength converting member, and radiations such as x-rays which have been converted into the sensitive wavelength region of the solid image pickup element by the wavelength converting member are guided by the imaging optical system and converted into an electric signal.
Still another object of the present invention is to provide a radiation image pickup device comprising a wavelength converting member for converting the wavelength of incident radiation into light; an imaging optical system for inputting thereto the light, as wavelength-converted by the wavelength converting member; a plurality of photosensors for receiving light from the imaging optical system; and a light transmissive substrate disposed between the photosensors and the wavelength converting member, for reducing x-rays that have passed through the wavelength converting member.
Yet still another object of the present invention is to provide a radiation image pickup device comprising a wavelength converting member for converting radiation into light; an erectly imaging optical system for inputting thereto the light from the wavelength converting member; and a plurality of photosensors for receiving the light from the erectly imaging optical system.
Yet still another object of the present invention is to provide a radiation image pickup system comprising a radiation image pickup device comprising a wavelength converting member for converting the wavelength of incident radiation into light; an imaging optical system for inputting thereto the light as wavelength-converted by the wavelength converting member; a plurality of photosensors for receiving light from the imaging optical system; and a light transmissive substrate disposed between the photosensors and the wavelength converting member, for reducing x-rays that have passed through the wavelength converting member; a signal processing means for processing a signal from the radiation image pickup device; a display means for displaying a signal from the signal processing means; and a radiation source for generating the radiation.
Yet still another object of the present invention is to provide a radiation image pickup system comprising a radiation image pickup device comprising a wavelength converting member for converting radiation into light; a normal rotation imaging optical system for inputting thereto the light from the wavelength converting member; and a plurality of photosensors for receiving the light from the normal rotation imaging optical system; a signal processing means for processing a signal from the radiation image pickup device; a display means for displaying a signal from the signal processing means; and a radiation source for generating the radiation.
In the present invention, the imaging optical system is disposed between the solid imaging element and the wavelength converting member, radiation such as x-rays, which has been converted into the sensitive wavelength region of the solid image pickup element by the wavelength converting member, is guided by the imaging optical system, and the radiation is converted into an electric signal by the plurality of photosensors. The radiation that has passed through the wavelength converting member is absorbed/shielded by a light transmissive member or a unity magnification normal rotation imaging optical system, so that irradiation of the photosensors or the like with the radiation is reduced or prevented.
This makes it possible to provide an irradiation image pickup device which is miniature, can stably read an image and has a high sensitivity.
Also, there can be provided an irradiation image pickup device that is high in the degree of freedom of the size of the image pickup region and can read a radiation image at a low cost with high performance.
In addition, the radiation image pickup system comprising the radiation image pickup device has high reliability and can reduce the amount of time and increase certainty of the diagnosis, and also can reduce the work necessary to prepare for radiography of an object and the cost for setting. Also, because the running cost of the system is reduced, the cost for non-destructive examination can be reduced.
Briefly describing an example of the radiation image pickup device according to the present invention, arranging a wavelength converting member that converts radiation into light, an imaging optical system that guides the light from the wavelength converting member, a light transmissive substrate and a two-dimensional photosensor that receives the light from the wavelength converting member in the direction of incidence of radiation in the mentioned order, results in a radiation image pickup device using a two-dimensionally arranged lens array as the optical system. Specific structural examples will be described in more detail with reference to the accompanying drawings in the following embodiments. The wavelength converting member such as a scintillator (phosphor) is made of a material used for wavelength-converting the radiation such as x-rays, xcex1-rays, xcex2-rays or xcex3-rays and generally means a material that converts the radiation into a light having a wavelength within the range of sensitive wavelengths of a photosensor.